The present invention relates to a display control method for a video display system and a video display system, and more particularly to a system for displaying video signals being supplied in a plurality of video display apparatuses, wherein display patterns of video of all the video display apparatuses are made to accord completely.
Conventionally, using the various video display elements such as a CRT (cathode-ray tube), a LCD (liquid crystal display), a PDP (plasma display panel), a DMD (digital micro-mirror device: the trademark of U.S. Texas Instruments Ltd.), the various video display apparatuses exist for displaying video produced by these video display elements on a picture surface.
As one kind of theses video display apparatuses the video display system exists in which a plurality of the video display apparatuses are arranged on the same plane to constitute the system and video of each of the video display apparatuses is combined to be displayed. The system concerned is utilized in case of materializing display for a big picture surface, display for a large number of split picture surfaces and the like.
The multi-panel display system is disclosed in JP-A-88820/1996, and the art described in the laid-open patent publication now will be explained as an example of the prior art.
FIG. 8A is an entire circuit block diagram illustrating the multi-panel display system according to the example of the prior art, and FIG. 8B is a circuit block diagram illustrating a master unit in the multi-panel display system of FIG. 8A.
The multi-panel display system shown in FIG. 8A comprises a system controller 501, a master unit 502 and slave units 503.
The master unit 502 shown in FIG. 8B comprises a video selector 521, a video processor 522, a PDP 523 and a controller 524.
When an input video signal, a display position and a size of the picture surface are designated by the system controller 501, the controller 524 of the master unit 502 selects input video in the video selector 521 in correspondence to said designation and carries out video processes such as expansion of the designated position and the like to display on the PDP 523.
The controller 524 of the master unit 502 further transmits control signals to each of the slave unit 503 via a control bus CI.
Each of the slave units 503 receives said control signals and carries out an expansion processing for the designated part of video of the input video signals in correspondence to the control signals and the like to display.
The art concerned is the art for controlling the expansion processing for some of video being displayed on each of the slave units by an instruction of the master units 502 and the like, which is not related to the control method for the display pattern in accordance with the present invention.
Additionally, the display apparatus for the multi-channel and split-picture surfaces is disclosed in JP-A-88820/2000, but the art concerned which also concerns the method for splitting the picture surface in a similar manner to said example of the prior art is not related to the control method of the display pattern in accordance with the present invention.
As with the multi-panel display system in accordance with said example of the prior art, it is disclosed neither as the problem to be solved nor as means to solve the problem to switch over the display patterns such as display widths being in horizontal/vertical directions in the PDP 523 and the like in correspondence to change in video characteristics such as a frequency and a polarity of horizontal/vertical synchronizing components and the like.
Hence, it is virtualized that in the multi-panel display system in accordance with said example of the prior art the above-mentioned processing can be realized by integrating in the master unit 502 and each of the slave units 503 a discriminating circuit of the video characteristics respectively of which each discriminates the video characteristics respectively to switch over if realization thereof is intended.
However, drawbacks to the virtual art included the following.
Firstly, there was the problem that variations in the times until which displaying video begins from this switching operation occurred among the master unit 502 and each of the slave units 503 when input video signals were switched over.
The reason is that the discriminating circuit of the video characteristics integrated in the master unit 502 and each of slave units 502 respectively judged the video characteristics independently and thereby the timing were not made to be synchronized at which the display patterns of the input video signals were switched over in accordance to these judged video characteristics.
Secondly, there were the problems that the different display patterns were displayed in some of the master unit 502 and the slave units 503, for example only one part of the picture surface was reduced to be displayed, some were displayed as pulled out of synchronization and the like when the input video signals were switched over.
The reason is that the master unit 502 and the slave units 502 were impossible to control so that all of the display patterns thereof always accorded, because the discriminating circuits of the video characteristics integrated in the master unit 502 and each of the slave units 503 respectively differed in operating principles, because the parameter ranges that were set as criteria for discrimination were different from each other even though the operating principles of the discriminating circuits for the video characteristics were the same, and because discrepancy between the parameter ranges occurred due to aged deterioration and the like.